How to use the chartpress.render_build_args function in chartpress

def test_render_build_args(git_repo):
    with open('chartpress.yaml') as f:
        config = yaml.load(f)
    for chart in config["charts"]:
        for name, options in chart["images"].items():
            build_args = render_build_args(
                options,
                {
                    'LAST_COMMIT': "sha",
                    'TAG': "tag",
                },
            )
            assert build_args == {
                'TEST_STATIC_BUILD_ARG': 'test',
                'TEST_DYNAMIC_BUILD_ARG': 'tag-sha',
            }